High-dose chemotherapy is increasingly evidenced to be neurotoxic and result in long-term neurocognitive sequelae. However, research investigating grey matter alterations in childhood cancer patients remains limited. As childhood sarcoma patients receive high-dose chemotherapy, we aimed to investigate cortical brain alterations in adult survivors. We analyzed high-resolution structural (T1-weighted) MRI and resting-state functional MRI (rsfMRI), to derive structural and functional cortical information in survivors of childhood sarcoma, treated with high-dose intravenous chemotherapy (n = 33). These scans were compared to age-and gender-matched controls (n = 34). Cortical volume and thickness were investigated using voxel-based morphometry and vertex-wise surface-based morphometry. Brain regions showing significant group differences in volume or thickness were implemented as seeds of interest to estimate their resting state co-activity with other areas (i.e. functional coherence). We explored whether structural measures were associated with potential risk factors, such as age at diagnosis, and cumulative doses of chemotherapeutic agents (methotrexate, ifosfamide). Finally, we investigated the link between functional regional strength, neurocognitive assessments and daily life complaints. In patients relative to controls we observed lower grey matter volumes in cerebellar and frontal areas, as well as frontal cortical thinning. Cerebellar volume and orbitofrontal thickness appeared dose-and age-related, respectively. Cortical thickness of the parahippocampal area appeared lower, only if the group comparison was not adjusted for depression. This region specifically showed lower functional coherence, which was associated with lower processing speed. This study suggests cortical thinning as well as decreased functional coherence in survivors of childhood sarcoma, which could be important for both long-term attentional functioning and emotional distress in daily life. Frontal areas might be specifically vulnerable during adolescence. Keywords Cortical development. Intravenous chemotherapy. Childhood sarcoma Highlights • Frontal, parahippocampal and cerebellar cortical thinning in childhood cancer survivors. • Cortical thinning appear chemotherapy dose-related as well as age-related. • Altered functional coherence in patients is associated with lower processing speed. Electronic supplementary material The online version of this article (https://doi. Brain Imaging and Behavior https://doi.